1. Field of the Invention
The present invention relates to a working range indicating device for an aerial ladder truck.
2. Description of the Prior Art
The detection of the degree of the ladder of an aerial ladder truck has heretofore been effected by an arrangement in which a number of microswitches are disposed side by side along the first ladder section and the second ladder section is used as a switch actuator. In order to indicate the degree of extension of the ladder, a number of neon lamps are disposed side by side longitudianally of a vertical angle indicating pointer and adapted to be turned on and off by said microswitches.
Such electric detection and indication system, however, can be easily affected by water unless it is made water-proof. Further, it is not only complicated in construction but also liable to develop troubles such as poor electric contact of the switches and mulfunction of the contacting mechanism. As a result, the reliablility in the indicating action has been low.